A carbon and nitrogen co-doped NiO electrochromic thin film, a smart window and a preparation method thereof

Abstract

The present invention discloses a carbon and nitrogen co-doped NiO electrochromic thin film and an intelligent window and a preparation method thereof, belonging to the technical field of electrochromic intelligent devices. A nickel salt is dissolved in absolute ethanol, ethanolamine is added, and stirred to form a nickel salt solution. The nickel salt solution is sprayed on the surface of a substrate and cured to obtain a carbon and nitrogen co-doped NiO electrochromic thin film. Since the carbon and nitrogen co-doped NiO can improve the conductivity of the material, the NiO thin film has higher coloring efficiency, faster response speed and good light regulation performance. At the same time, the amorphous crystal structure can avoid the structural collapse caused by volume expansion, thereby improving the cycle stability, being applicable to fields such as building energy-saving windows, and having broad market prospects and application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochromic intelligent devices, and particularly relates to a carbon and nitrogen co-doped NiO electrochromic thin film, an intelligent window, and a preparation method thereof. Background Art

[0002] In recent years, electrochromic technology has received extensive attention in the field of building energy conservation. Due to its large spectral modulation amplitude, high coloring efficiency, fast response speed, and the ability to achieve active or on-demand regulation, it is widely regarded as the best solution for preparing intelligent energy-saving windows.

[0003] Nickel oxide (NiO) is a commonly used electrochromic positive electrode material. When a positive voltage is applied, the thin film changes from transparent to brown; when a reverse voltage is applied, the thin film returns to the transparent state. The NiO crystal has a cubic structure similar to NaCl, with a closely packed lattice arrangement, which is not conducive to the insertion and extraction of electrolyte ions. Therefore, its electrochromic cycle stability is poor. Researchers have adopted a series of strategies to improve its various performance indicators, including element doping, coating with conductive substances, microtopography regulation, selection of electrolyte ions, design of porous / mesoporous / amorphous structures, synthesis of quantum dots, etc. For example, the literature (Materials Chemistry and Physics 306(2023)128079) discloses an Sn-doped amorphous NiO. Since Sn 4+ replaces part of Ni 2+ , the number of Ni vacancies increases. During the electrochromic process, a part of Ni 2+ is more easily converted to Ni 3+ , effectively accelerating the electron transfer rate, and at the same time, the cycle life is increased to 30,000 times. The preparation of high-quality electrochromic thin films requires providing a good diffusion channel for electrons and ions, and the pore channels between particles can effectively accommodate volume expansion. However, most current nickel oxide electrochromic materials still cannot meet this requirement. At the same time, the preparation of thin films generally uses hydrothermal methods, electrochemical deposition methods, magnetron sputtering methods, sol-gel methods, etc., which are not suitable for large-scale preparation of large-area electrochromic films. Thus, although significant achievements have been made in laboratory research on nickel oxide, its preparation process and cost issues are still the main obstacles restricting its large-scale application. Therefore, developing a simple, efficient, and cost-controllable preparation method for nickel oxide electrochromic thin films has important practical application value and broad market prospects. Summary of the Invention

[0004] The present invention provides a carbon and nitrogen co-doped NiO electrochromic thin film, an intelligent window, and a preparation method thereof to solve the problems of high material synthesis difficulty, high synthesis cost, complex film-forming equipment, and poor film uniformity in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] A preparation method of a carbon and nitrogen co-doped NiO electrochromic thin film, comprising the following steps:

[0008] Dissolve a nickel salt in absolute ethanol, add ethanolamine, stir to form a nickel salt solution, spray the nickel salt solution on the surface of a substrate, and obtain a carbon and nitrogen co-doped NiO electrochromic thin film after curing.

[0009] In the present invention, the function of ethanolamine is as follows:

[0010] 1. Chelating agent function

[0011] Ethanolamine has two functional groups, an amino group (-NH 2 ) and a hydroxyl group (-OH), which enables it to form a coordination complex with nickel ions (Ni 2+ ). Through chelation, ethanolamine can stabilize the dispersion of nickel ions in the solution, prevent premature precipitation of nickel ions or formation of non-uniform particles. This helps to maintain the homogeneity and stability of the solution, and thus obtain a more uniform nickel oxide thin film in the subsequent spraying and thin film formation processes.

[0012] 2. Adjust the pH value of the solution

[0013] Ethanolamine is a weak base, and it can partially neutralize the acidity in the solution to adjust the pH value of the solution. An appropriate pH value can control the hydrolysis rate of the nickel salt and the formation conditions of nickel oxide, thus helping to form the desired nickel oxide (NiO) structure and properties.

[0014] 3. Increase the viscosity of the solution

[0015] The addition of ethanolamine can increase the viscosity of the solution, which is very important for the spraying process. Appropriate viscosity helps to form a uniform solution layer and prevent the droplets from flowing too fast during spraying, thus achieving uniform film coverage.

[0016] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic thin film, the concentration of the nickel salt solution is 0.05 - 0.5 mol / L.

[0017] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic thin film, the substrate is conductive glass, and more preferably ITO conductive glass.

[0018] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic thin film, the nickel salt is a soluble nickel salt, including nickel acetate, nickel chloride, nickel nitrate or nickel sulfate.

[0019] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic thin film, the ratio of the volume of ethanolamine to the amount of substance of nickel salt is (50-1000) mL∶(1-10) mol.

[0020] The influence of the ratio of the volume of ethanolamine to the amount of substance of nickel salt on the film properties is as follows:

[0021] 1. Crystallinity and structure of the film

[0022] As the proportion of ethanolamine increases: Ethanolamine is a chelating agent that can form stable complexes with nickel ions, which will affect the crystallinity of nickel oxide (NiO) in the film. A higher ethanolamine content may lead to a more uniform film structure, but may also reduce the grain size, resulting in a decrease in film crystallinity.

[0023] Higher proportion of nickel acetate: There will be more nickel sources for the growth of the film, which may lead to higher crystallinity. However, if the ethanolamine is insufficient, it may cause uneven distribution of nickel ions during deposition, resulting in an increase in film defects.

[0024] 2. Electrochromic properties of the film

[0025] Moderate proportion of ethanolamine: An appropriate amount of ethanolamine can ensure uniform deposition of nickel sources, forming a dense NiO film, which helps to improve the electrochromic efficiency and cycling stability of the film.

[0026] Too high proportion of ethanolamine: It may cause excessive complexation of nickel ions during deposition, reducing the effective deposition amount of NiO, and the electrochromic properties of the film may thus be reduced.

[0027] 3. Surface morphology of the film

[0028] The proportion of ethanolamine affects the surface smoothness: Ethanolamine can regulate the viscosity and complex state of the solution, which will directly affect the leveling property and adhesion of the film on the substrate. Too much ethanolamine may make the film surface smoother, but if too little, it may cause the film surface to be uneven or even cracked.

[0029] 4. Chemical composition and doping effect

[0030] Carbon and nitrogen doping effect: Ethanolamine contains nitrogen and carbon sources, which can introduce carbon and nitrogen elements into the NiO lattice during high-temperature heat treatment. Different ratios may affect the doping degree, thereby changing the optical band gap, conductivity and other properties of the film.

[0031] 5. Conductivity and electrochemical properties of the film

[0032] Uniformity of carbon and nitrogen element doping: When the proportion of ethanolamine is appropriate, the doping may be relatively uniform, which helps to improve the conductivity and electrochemical properties of the thin film. If the proportion is unbalanced, non-uniform doping may lead to a decrease in the conductivity of the thin film, affecting the response speed and cycle stability of electrochromism.

[0033] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic thin film, the curing is heat treatment, the temperature of the heat treatment is 150 - 300 °C, and the time is 0.5 - 1.5 h. The level of the heat treatment temperature determines the compositional change of the solute in the solution. As the temperature increases, the solute gradually changes from an organic mixture at the beginning to an inorganic substance, and the color-changing performance shows a process of first increasing and then decreasing.

[0034] The second technical solution of the present invention:

[0035] The present invention provides a carbon and nitrogen co-doped NiO electrochromic thin film obtained according to the above preparation method.

[0036] The third technical solution of the present invention:

[0037] The present invention also provides a carbon and nitrogen co-doped NiO electrochromic glass, with a carbon and nitrogen co-doped NiO electrochromic thin film coated on its surface.

[0038] The fourth technical solution of the present invention:

[0039] The present invention also provides a carbon and nitrogen co-doped NiO electrochromic smart window, prepared from the above carbon and nitrogen co-doped NiO electrochromic thin film or the above carbon and nitrogen co-doped NiO electrochromic glass.

[0040] The fifth technical solution of the present invention:

[0041] The present invention also provides a preparation method of the above-mentioned carbon and nitrogen co-doped NiO electrochromic smart window. When it is prepared from the above carbon and nitrogen co-doped NiO electrochromic thin film, the preparation method includes the following steps: Coating the carbon and nitrogen co-doped NiO electrochromic thin film on the surface of conductive glass to obtain glass coated with the carbon and nitrogen co-doped NiO electrochromic thin film, overlapping it with another conductive glass, injecting electrolyte between the glass coated with the carbon and nitrogen co-doped NiO electrochromic thin film and the conductive glass, sealing, and connecting an external circuit to obtain the carbon and nitrogen co-doped NiO electrochromic smart window;

[0042] When it is prepared from the above carbon and nitrogen co-doped NiO electrochromic glass, the preparation method includes the following steps: Overlapping the carbon and nitrogen co-doped NiO electrochromic glass with conductive glass, injecting electrolyte between the carbon and nitrogen co-doped NiO electrochromic glass and the conductive glass, sealing, and connecting an external circuit to obtain the carbon and nitrogen co-doped NiO electrochromic smart window.

[0043] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic smart window, the conductive glass is ITO conductive glass.

[0044] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic smart window, the thickness of the carbon and nitrogen co-doped NiO electrochromic thin film is 50 - 500 nm, more preferably 150 - 350 nm. In the present invention, the main factor causing different film thicknesses is the spraying amount.

[0045] Preferably, in the preparation method of the carbon and nitrogen co-doped NiO electrochromic smart window, the electrolyte is a potassium hydroxide (KOH) solution with a concentration of 0.1 - 1.0 mol / L.

[0046] Aspect six of the technical solution of the present invention:

[0047] The present invention also provides the application of the above carbon and nitrogen co-doped NiO electrochromic thin film or the above carbon and nitrogen co-doped NiO electrochromic glass in an electrochromic smart window.

[0048] When the above electrochromic smart window is applied with a voltage, the color changes from colorless and transparent to brownish black.

[0049] Compared with the prior art, the present invention has the following advantages and technical effects:

[0050] 1. Since carbon and nitrogen co-doped NiO can improve the conductivity of the material, the NiO thin film has higher coloring efficiency, faster response speed and good light regulation performance. At the same time, the amorphous crystal structure can avoid the structural collapse caused by volume expansion, so that the cycle stability can be increased to more than 5000 times, which is applicable to fields such as building energy-saving windows and has broad market prospects and application potential.

[0051] 2. The present invention uses a simple and easy-to-operate spraying method to prepare a carbon and nitrogen co-doped NiO thin film on ITO conductive glass, and the target product can be obtained through appropriate heat treatment. The entire preparation process does not require complex equipment and processes, reducing production costs and technical thresholds, and is suitable for large-scale and large-area production and application. At the same time, the prepared thin film is ejected by compressed air and immediately adheres to the glass surface, and the solvent in the solution is volatilized at a suitable temperature. During a single spraying operation, it experiences repeated ejection, adhesion, and separation and volatilization of the solvent and solute at intervals, regularly, and relatively evenly. The solute has a strong binding force with the glass, and after a long-time heat treatment at a suitable temperature, the adhesion of the thin film is further improved. Therefore, the thin film is not easy to fall off during long-term use, ensuring the long-term stability and reliability of the smart window.

[0052] 3. The present invention uses environmentally friendly solvents such as anhydrous ethanol and ethanolamine, reducing the emission of harmful gases compared to traditional methods such as chemical vapor deposition. In addition, raw materials such as nickel acetate, nickel chloride, nickel nitrate, and nickel sulfate are relatively inexpensive, further reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0054] Figure 1 is a physical picture of the coloring / fading of the carbon and nitrogen co-doped nickel oxide electrochromic smart window of Example 1;

[0055] Figure 2 is an SEM image of the carbon and nitrogen co-doped nickel oxide electrochromic thin film glass of Example 1, where a is the SEM image of the surface of the carbon and nitrogen co-doped nickel oxide electrochromic thin film glass; b is the SEM image of the cross-section of the carbon and nitrogen co-doped nickel oxide electrochromic thin film glass;

[0056] Figure 3 is a TEM image of the carbon and nitrogen co-doped nickel oxide electrochromic thin film of Example 1;

[0057] Figure 4 is an electron diffraction pattern of the carbon and nitrogen co-doped nickel oxide electrochromic thin film of Example 1;

[0058] Figure 5 is an energy spectrum elemental analysis diagram of the carbon and nitrogen co-doped nickel oxide electrochromic thin film of Example 1;

[0059] Figure 6 is a light transmittance diagram of the carbon and nitrogen co-doped NiO electrochromic smart window of Example 1 during coloring / fading;

[0060] Figure 7 is a response time diagram of the carbon and nitrogen co-doped NiO electrochromic smart window of Example 1;

[0061] Figure 8 is a light transmittance diagram of the carbon and nitrogen co-doped NiO electrochromic smart window of Example 2 during coloring / fading;

[0062] Figure 9 is a response time diagram of the carbon and nitrogen co-doped NiO electrochromic smart window of Example 2;

[0063] Figure 10 is a light transmittance diagram of the carbon and nitrogen co-doped NiO electrochromic smart window of Comparative Example 3 during coloring / fading;

[0064] Figure 11Response time graph of the carbon and nitrogen co-doped NiO electrochromic smart window of Comparative Example 3. Detailed implementation manners

[0065] The various exemplary implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and implementation manners of the present invention.

[0066] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0067] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0068] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0069] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0070] Unless otherwise specified, the room temperature in the present invention is calculated as 25 ± 2 °C.

[0071] All raw materials used in the examples of the present invention are obtained by purchasing commercially.

[0072] The technical solutions of the present invention will be further described below through examples.

[0073] Example 1

[0074] This example provides a carbon and nitrogen co-doped NiO electrochromic thin film and a smart window, and its preparation method is as follows:

[0075] (1) Weigh 0.497 g (3 mmol) of nickel acetate and dissolve it in 20 mL of absolute ethanol. Add 120 μL of ethanolamine and mix and stir evenly to form a green, clear and transparent solution (i.e., the nickel salt solution). In this example, the concentration of the nickel salt solution is 0.15 mol / L;

[0076] (2) Take 2 mL of the above nickel salt solution and spray it on the surface of a cleaned ITO conductive glass (6 cm * 7 cm, the same below). After heat treatment at 250 °C for 1.5 hours, a carbon and nitrogen co-doped NiO electrochromic thin film glass is obtained (in this step, the carbon and nitrogen co-doped NiO electrochromic thin film can be obtained by peeling it off from the ITO conductive glass);

[0077] (3) Dissolve potassium hydroxide (KOH) in 40 mL of water to obtain an electrolyte with a concentration of 0.1 mol / L;

[0078] (4) Stack the carbon and nitrogen co-doped NiO electrochromic thin film glass with another ITO conductive glass, inject the above electrolyte between the carbon and nitrogen co-doped NiO electrochromic thin film glass and the ITO conductive glass, seal it, and connect the external circuit to obtain a carbon and nitrogen co-doped NiO electrochromic smart window.

[0079] The carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example was subjected to a simulation test, and its coloring / fading physical pictures are as Figure 1 shown. As can be seen from Figure 1 , at room temperature, the smart window presents a highly transparent state (corresponding to the leftmost one); when a voltage of 1 V is applied, the smart window colors and presents a brownish-black color (corresponding to the fourth from the left); when a voltage of -0.5 V is applied, the smart window fades and returns to the highly transparent state (corresponding to the second from the left). After 3000 cycles, it can still return to the highly transparent state (corresponding to the third from the left).

[0080] The glass of the carbon and nitrogen co-doped NiO electrochromic thin film prepared in this example was subjected to SEM testing, and the results are as Figure 2 shown. As can be seen from Figure 2 , the NiO nano-thin film is evenly sprayed on the surface of the conductive glass, and the particles are regular spherical shapes with a size of 30 - 80 nm. Moreover, from the cross-section, the thickness of the thin film is about 50 - 150 nm, and it is tightly combined with the substrate.

[0081] The glass of the carbon and nitrogen co-doped NiO electrochromic thin film prepared in this example was subjected to TEM testing, electron diffraction, and energy spectrum analysis, and the results are as Figure 3 、 4 、5 shown. As can be seen from Figure 3 , the NiO nanoparticles are flaky; as can be seen from Figure 4It can be seen that the NiO nanoparticles are not crystallized and have an amorphous crystal structure, which can avoid the structural collapse caused by volume expansion, thereby improving the cycling stability. From Figure 5 it can be seen that in addition to containing Ni and O elements, the NiO nanoparticles also contain C and N elements.

[0082] Apply a voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during coloring and fading. The results are as Figure 6 shown. From Figure 6 it can be seen that the modulation amplitude of the visible light transmittance at 500 nm (i.e., the spectral modulation amplitude in Table 1) reaches 57.7%, and the modulation amplitude can still remain above 80% after 5000 cycles.

[0083] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, cyclic tests are carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance varying with time is measured. The results are as Figure 7 shown. From Figure 7 it can be seen that during each electrochromic process (one coloring and one fading), the coloring time is 11 s and the fading time is 7 s.

[0084] Example 2

[0085] This example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that the heat treatment temperature is changed to 150 °C.

[0086] Apply a voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during coloring and fading. The results are as Figure 8 shown. From Figure 8 it can be seen that the modulation amplitude of the visible light transmittance at 500 nm is 27.3%, and the modulation amplitude still remains above 80% after 3000 cycles.

[0087] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, cyclic tests are carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance varying with time is measured. The results are as Figure 9 shown. From Figure 9 it can be seen that during each electrochromic process (one coloring and one fading), the coloring time is 7 s and the fading time is 7 s.

[0088] Example 3

[0089] This example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that the heat treatment temperature is changed to 200 °C.

[0090] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during bleaching. The modulation amplitude of the visible light transmittance at 500 nm is 37.7%, and the modulation amplitude still remains above 80% after 2500 cycles.

[0091] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, perform cyclic tests by coloring at +1V for 30 s and bleaching at -0.5V for 30 s, and measure the curve of transmittance changing with time. During each electrochromic process (one coloring and one bleaching), the coloring time is 6.0 s and the bleaching time is 19.0 s.

[0092] Example 4

[0093] This example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that both the heat treatment temperature and the heat treatment time are changed, so that the heat treatment temperature is 150 °C and the heat treatment time is 30 min.

[0094] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during bleaching. The modulation amplitude of the visible light transmittance at 500 nm is 23.7%, and the modulation amplitude still remains above 80% after 1000 cycles.

[0095] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, perform cyclic tests by coloring at +1V for 30 s and bleaching at -0.5V for 30 s, and measure the curve of transmittance changing with time. During each electrochromic process (one coloring and one bleaching), the coloring time is 5.5 s and the bleaching time is 14.1 s.

[0096] Example 5

[0097] This example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Comparative Example 1, except that both the heat treatment temperature and the heat treatment time are changed, so that the heat treatment temperature is 300 °C and the heat treatment time is 30 min.

[0098] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during bleaching. The modulation amplitude of the visible light transmittance at 500 nm is 46.4%, and the modulation amplitude still remains above 80% after 2000 cycles.

[0099] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, cyclic tests were carried out by coloring at +1V for 30s and fading at -0.5V for 30s, and the curve of transmittance changing with time was measured. During each electrochromic process (one coloring and one fading), the coloring time was 7.9s and the fading time was 22.1s.

[0100] Example 6

[0101] (1) Weigh 1.296 g (10 mmol) of nickel chloride and dissolve it in 20 mL of absolute ethanol. Add 500 μL of ethanolamine and mix and stir evenly to form a green clear and transparent solution (i.e., nickel salt solution). In this example, the concentration of the nickel salt solution is 0.5 mol / L;

[0102] (2) Take 2 mL of the above solution and spray it on the surface of the cleaned ITO conductive glass, and heat-treat it at 250 °C for 1.5 hours to obtain a carbon and nitrogen co-doped NiO electrochromic thin film glass;

[0103] (3) Dissolve KOH in 40 mL of water to obtain an electrolyte with a concentration of 0.5 mol / L;

[0104] (4) Stack the carbon and nitrogen co-doped NiO electrochromic thin film glass with another ITO conductive glass, inject the above electrolyte between the carbon and nitrogen co-doped NiO electrochromic thin film glass and the conductive glass, seal it, and connect the external circuit to obtain a carbon and nitrogen co-doped NiO electrochromic smart window.

[0105] Apply a voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during coloring and fading. The modulation amplitude of the visible light transmittance at 500 nm is 13.3%, and the modulation amplitude still remains above 80% after 1000 cycles.

[0106] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, cyclic tests were carried out by coloring at +1V for 30s and fading at -0.5V for 30s, and the curve of transmittance changing with time was measured. During each electrochromic process (one coloring and one fading), the coloring time was 18.4s and the fading time was 31.1s.

[0107] Example 7

[0108] (1) Weigh 0.183 g (1 mmol) of nickel nitrate and dissolve it in 20 mL of absolute ethanol. Add 100 μL of ethanolamine and mix and stir evenly to form a green clear and transparent solution (i.e., nickel salt solution). In this example, the concentration of the nickel salt solution is 0.05 mol / L;

[0109] (2) Take 2 mL of the above solution and spray it on the surface of a cleaned ITO conductive glass. After heat treatment at 250 °C for 1.5 hours, a carbon and nitrogen co-doped NiO electrochromic thin film glass is obtained;

[0110] (3) Dissolve KOH in 40 mL of water to obtain an electrolyte solution with a concentration of 1.0 mol / L;

[0111] (4) Stack the carbon and nitrogen co-doped NiO electrochromic thin film glass with another ITO conductive glass. Inject the above electrolyte solution between the carbon and nitrogen co-doped NiO electrochromic thin film glass and the conductive glass, seal it, and connect the external circuit to obtain a carbon and nitrogen co-doped NiO electrochromic smart window.

[0112] Apply a voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, and measure the light transmittance during coloring and fading. The modulation amplitude of the visible light transmittance at 500 nm is 35.9%, and the modulation amplitude still remains above 80% after 1000 cycles.

[0113] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, perform cyclic tests by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and measure the curve of the transmittance changing with time. During each electrochromic process (one coloring and fading), the coloring time is 16.9 s and the fading time is 24.1 s.

[0114] Example 8

[0115] (1) Weigh 0.774 g (5 mmol) of nickel sulfate and dissolve it in 20 mL of absolute ethanol. Add 50 μL of ethanolamine and mix and stir evenly to form a green clear and transparent solution (i.e., nickel salt solution). In this example, the concentration of the nickel salt solution is 0.25 mol / L;

[0116] (2) Take 2 mL of the above solution and spray it on the surface of a cleaned ITO conductive glass. After heat treatment at 250 °C for 1.5 hours, a carbon and nitrogen co-doped NiO electrochromic thin film glass is obtained;

[0117] (3) Dissolve KOH in 40 mL of water to obtain an electrolyte solution with a concentration of 0.5 mol / L;

[0118] (4) Stack the carbon and nitrogen co-doped NiO electrochromic thin film glass with another ITO conductive glass. Inject the above electrolyte solution between the carbon and nitrogen co-doped NiO electrochromic thin film glass and the conductive glass, seal it, and connect the external circuit to obtain a carbon and nitrogen co-doped NiO electrochromic smart window.

[0119] The carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example was applied with a voltage, and the light transmittance during fading was measured. The modulation amplitude of the visible light transmittance at 500 nm was 25.0%, and the modulation amplitude remained above 80% after 1500 cycles.

[0120] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this example, cyclic tests were carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance changing with time was measured. During each electrochromic process (one coloring and one fading), the coloring time was 18.6 s and the fading time was 25.7 s.

[0121] Comparative Example 1

[0122] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that the KOH electrolyte is changed to a polycarbonate solution in which LiClO 4 is dissolved, and its concentration is 1 mol / L.

[0123] A voltage was applied to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and it was found that it did not change color.

[0124] Reasons for performance degradation: OH - is more likely to be embedded and removed, and the process is relatively rapid. It is relatively easier to observe color change in a short time, and NiO usually exhibits good electrochromic performance in alkaline electrolytes; while Li + has a slower embedding and removal process, and the embedding / removal process is not sufficient or strong enough to cause a significant redox reaction of the NiO film, thus unable to effectively change the optical properties of the material.

[0125] Comparative Example 2

[0126] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that the heat treatment time is changed to 60 min.

[0127] A voltage was applied to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and the light transmittance during fading was measured. The modulation amplitude of the visible light transmittance at 500 nm was 19.1%.

[0128] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests were carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance changing with time was measured. During each electrochromic process (one coloring and one fading), the coloring time was 8.0 s and the fading time was 14.0 s.

[0129] Reasons for performance degradation: The heat treatment time is short, the amount of transformed discoloring substances is small, the discoloring activity decreases, and the modulation amplitude decreases.

[0130] Comparative Example 3

[0131] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, the preparation method of which is the same as that of Comparative Example 1, except that the heat treatment temperature is changed to 350 °C.

[0132] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and measure the light transmittance during coloring and fading. The results are as Figure 10 shown. It can be seen from Figure 10 that the modulation amplitude of the visible light transmittance at 500 nm is 15.5%, and the modulation amplitude remains at about 80% after 800 cycles.

[0133] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests are carried out by coloring at +1 V for 10 s and fading at -0.5 V for 20 s, and the curve of transmittance changing with time is measured. The results are as Figure 11 shown. It can be seen from Figure 11 that during each electrochromic process (one coloring and fading), the coloring time is 6.0 s and the fading time is 11.0 s.

[0134] Reasons for performance degradation: The heat treatment temperature is high, the discoloring substances are transformed into NiO, the discoloring activity decreases, and the modulation amplitude decreases.

[0135] Comparative Example 4

[0136] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, the preparation method of which is the same as that of Comparative Example 1, except that both the heat treatment temperature and the heat treatment time are changed, the heat treatment temperature is 300 °C, and the heat treatment time is 60 min.

[0137] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and measure the light transmittance during coloring and fading. The modulation amplitude of the visible light transmittance at 500 nm is 8.9%, and the modulation amplitude remains at about 80% after 700 cycles.

[0138] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests are carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and the curve of transmittance changing with time is measured. During each electrochromic process (one coloring and fading), the coloring time is 9.2 s and the fading time is 16.6 s.

[0139] Reasons for performance degradation: The heat treatment temperature is relatively high, the content of inactive substances increases, the discoloration activity decreases, and the spectral modulation amplitude decreases.

[0140] Comparative Example 5

[0141] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Comparative Example 1, except that both the heat treatment temperature and the heat treatment time are changed, so that the heat treatment temperature is 300 °C and the heat treatment time is 90 min.

[0142] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and measure the light transmittance during coloring and fading. The modulation amplitude of the visible light transmittance at 500 nm is 5.4%, and the modulation amplitude remains at about 80% after 500 cycles.

[0143] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests are carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance changing with time is measured. During each electrochromic process (one coloring and fading), the coloring time is 7.3 s and the fading time is 12.4 s.

[0144] Reasons for performance degradation: The heat treatment temperature is relatively high, the content of inactive substances increases, the discoloration activity decreases, and the spectral modulation amplitude decreases.

[0145] Comparative Example 6

[0146] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Comparative Example 1, except that the amount of the spraying solution is changed, so that the volume of the spraying solution is 1 mL, and the film thickness is about 50 - 150 nm. It does not change color after applying voltage.

[0147] Reasons for performance degradation: The volume of the spraying solution is too small, resulting in too little active substance in the film on the glass surface after heat treatment. After power-on, the modulation amplitude decreases significantly, and obvious discoloration cannot occur.

[0148] Comparative Example 7

[0149] This comparative example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Comparative Example 1, except that the amount of the spraying solution is changed, so that the volume of the spraying solution is 3 mL, and the film thickness is about 300 - 500 nm.

[0150] Apply voltage to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and measure the light transmittance during coloring and fading. The modulation amplitude of the visible light transmittance at 500 nm is 4.5%, and the modulation amplitude remains at 60% after 500 cycles.

[0151] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests were carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance changing with time was measured. During each electrochromic process (one coloring and fading), the coloring time was 8.7 s and the fading time was 20.5 s.

[0152] Reasons for performance degradation: The film was too thick, which hindered the insertion and extraction of ions, and the migration paths of charges and ions became longer, resulting in a decrease in the response speed of electrochromism and failing to achieve the effect of rapid color change. Moreover, the too-thick film might absorb too much light during the color change process, leading to a reduction in the optical difference between the transparent and colored states, thereby reducing the spectral modulation amplitude.

[0153] Comparative Example 8

[0154] This example provides a carbon and nitrogen co-doped NiO electrochromic smart window, and its preparation method is the same as that of Example 1, except that ethanolamine is not added.

[0155] A voltage was applied to the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, and the light transmittance during coloring and fading was measured. The modulation amplitude of the visible light transmittance at 500 nm was 4.4%, and the modulation amplitude remained at 60% after 200 cycles.

[0156] During the electrochromic process of the carbon and nitrogen co-doped NiO electrochromic smart window prepared in this comparative example, cyclic tests were carried out by coloring at +1 V for 30 s and fading at -0.5 V for 30 s, and a graph of the transmittance changing with time was measured. During each electrochromic process (one coloring and fading), the coloring time was 7.0 s and the fading time was 18.0 s.

[0157] Reasons for performance degradation: In the absence of ethanolamine, nickel ions (Ni 2+ ) might be more likely to aggregate in the solution, resulting in uneven, rough or porous regions in the film during the deposition process. Moreover, without adding ethanolamine, the doping amounts of carbon and nitrogen in the film might be significantly reduced or completely absent, thereby leading to a decrease in the electrochromic activity, response speed and stability of the film.

[0158] A voltage was applied to the carbon and nitrogen co-doped NiO electrochromic smart windows prepared in Examples 1 to 5 and Comparative Examples 2 to 7, and the light transmittance during coloring / fading was measured. The results are shown in Table 1.

[0159] Table 1 Test results of the light transmittance of the carbon and nitrogen co-doped NiO electrochromic smart window at 500 nm

[0160]

[0161] Note: In Table 1, "volume of the solution" refers to the spraying volume of the nickel salt solution.

[0162] As can be seen from Table 1, when the KOH aqueous solution is used as the electrolyte, the spectral modulation amplitude fluctuates within a large range. The optimal conditions are that the spraying solution volume is 2 mL, the heat treatment temperature is 250 °C, and the heat treatment time is 90 min. The maximum spectral modulation amplitude can reach 57.7%. It can effectively regulate the visible light transmittance in summer and meet the requirements for light transmission and light shielding in the coloring / fading state, playing the role of lighting, regulating the indoor temperature or protecting privacy. Moreover, the voltage required for the electrochromism of the device is small (0.6 V), which can effectively simplify the structural components of the smart window, save energy, and has high stability.

[0163] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a carbon-nitrogen co-doped NiO electrochromic smart window, characterized in that: Here are the steps: (1) Weigh 0.497 g of nickel acetate and dissolve it in 20 mL of anhydrous ethanol, add 120 μL of ethanolamine, mix and stir evenly to form a green, clear and transparent nickel salt solution, the concentration of the nickel salt solution is 0.15 mol / L; (2) Spray 2 mL of the nickel salt solution onto a cleaned 6 cm*7 cm ITO conductive glass surface, and heat treat at 250° C. for 1.5 hours to obtain a carbon-nitrogen co-doped NiO electrochromic thin film glass. In this step, the carbon-nitrogen co-doped NiO electrochromic thin film is torn off from the ITO conductive glass to obtain a carbon-nitrogen co-doped NiO electrochromic thin film; (3) Dissolve potassium hydroxide in 40 mL of water to obtain a 0.1 mol / L electrolyte; (4) stacking the carbon-nitrogen co-doped NiO electrochromic thin film glass and another ITO conductive glass, injecting the above electrolyte between the carbon-nitrogen co-doped NiO electrochromic thin film glass and the ITO conductive glass, sealing, and connecting an external circuit to obtain a carbon-nitrogen co-doped NiO electrochromic smart window; NiO nanoparticles are not crystallized, and have an amorphous crystal structure. In addition to Ni and O elements, NiO nanoparticles also contain C and N elements; After 3000 cycles, the carbon-nitrogen co-doped NiO electrochromic smart window can still return to a highly transparent state; the modulation amplitude of visible light transmittance at 500nm reaches 57.7%, and the modulation amplitude can still be maintained above 80% after 5000 cycles.

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